marketing gimick. I doubt that wood cone drivers will offer superior sound quality over metallic cone drivers which will hardly flex and therefore cause hardly any distortion. I would definitely check them out before I dismiss them, but I'm not holding my breath.
I would think that wood cones would be fantastic in a home environment where humidity and temperature could be regulated within a narrow margin. A car audio application seems very unlikely. Just try leaving your Stradivarius or Steinway outside and see how good it sounds in a year.